>>140090
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Thsi reaction is pretty simple compared to the use of gaseous NH3, but the claime dyields are still not attained. Toluene seems to be a much more selective solvent for the extarction than AcOEt is, giving a much cleaner product. The workup still needs optimizing though. Direct fractionnation isn't possibble becasue of the large amounts of inorganic solids present in the syrup. Using diethyl ether as in the patent's procedure, or DCM wasn't possible because of the ambient temp >35°C here (hot...). Tolueneseems pretty eefctive, but still requires large amounts of solvent. I guess a gradaully distn of the solvent, and extarction with the recycled toluene could be the best option, as the extract seems pretty clean. Fractionnation of the TAA freebase might be a better option than direct acidification, it is pretty clear there is a resinous product appering near the end of the acidification, covering the TAA.HSO4.

Forming the hydrate or oxalate after fractionnation should give a pure product, stable as is. I will try another variation of the reaction, possibly letting it heat up during the addition s is mentionned in the patent. I'm sure the yield is good, and that the isolation of the product is problematic (TAA freebase is pretty soluble in water).

I think we are in the good direction though. Using only ammonia could be more practical, or at least catalytic amount s of ammonium nitrate (apart from the extarction, producing dry NH4NO3 is the lengthy part).

I still have some NH4NO3 left, so will try another recation with a smaller NH4NO3/NH4OH ratio, but same acetone/ammonia donor ratio.

According to the patent, excellent selectivities to TAA are possible at RT, the acetone/ammonia ratio seems to be more important than the temp regarding acetonine/DAA formation.